The present invention relates to a cephalosporin derivative represented by the formula (I): ##STR2## wherein R.sup.1 represents a halogenoalkyl group of 1 to 4 carbon atoms, a salt thereof and an ester thereof, and a process for producing the cephalosporin derivative.
The invention also relates to a pharmaceutical composition and antibacterial agent comprising as an active ingredient, the cephalosporin derivative, and a method for the treatment of infectious diseases comprising administering to a patient suffering therefrom a pharmaceutically effective amount of the cephalosporin derivative.
The cephalosporin antibiotics are now broadly used and they are excellent medicines because of their prominent selective toxicity against bacteria. Although the conventional cephalosporins show a broad antibacterial activity against Gram-positive and Gram-negative bacteria while showing a high stability against .beta.-lactamase, they have a serious defect, that is, they show a low stability in blood resulting in a short duration of their antibacterial activity in the living body.
As a result of the present inventors' studies for finding a cephalosporin derivative without showing such a defect, it has been found by the present inventors that a cephalosporin derivative represented by the formula (I) shows a high antibacterial activity and a high stability in blood.
Further, the present inventors have found that an ester of the cephalosporin derivative shows a low antibacterial activity, but the compounds are converted into a free acid thereof, that is, a cephalosporin derivative represented by the formula (I), thereby showing a high antibiotic activity, and have attained the present invention.
Accordingly, the object of the present invention is to provide a cephalosporin derivative showing a prolonged antibacterial activity due to a high stability thereof in blood.
Also, the object of the present invention is to provide the cephalosporin derivative showing a low antibacterial activity in the intestinal tract, however, showing a high and prolonged antibacterial activity due to the conversion into a free acid when absorbed from the intestinal tract into the blood.